This section is intended to provide a background or context to the invention disclosed below. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise explicitly indicated herein, what is described in this section is not prior art to the description in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:
3GPP Third Generation Partnership Project
ACK Acknowledge
AGC Automatic Gain Control
ARQ Automatic Repeat reQuest
C-RNTI Cell-RNTI
D2D Device-to-Device
DL DownLink (from base station to user equipment)
DMRS DeModulation Reference Signal
eNB or eNode B evolved Node B (LTE base station)
GP Guard Period
ID identification
ISM Industrial Scientific Medical
LTE Long Term Evolution
MAC Media Access Control
M2M Machine-to-Machine
MCS Modulation and Coding Scheme
MME Mobility Management Entity
MTC Machine-Type Communication
NACK Negative Acknowledge
NCE Network Control Element
OFDM Orthogonal Frequency Division Multiplexing
PCC Primary Component Carrier
Pcell Primary cell
PDCCH Physical Downlink Control CHannel
PHICH Physical Hybrid ARQ CHannel
PHY physical layer (L1)
PUSCH Physical Uplink Shared CHannel
PSS Primary Synchronization Signal
RB Resource Block
Rel Release
RNTI Radio Network Temporary Identifier
RRC Radio Resource Control
Rx Receiver or reception
SCC Secondary Component Carrier
Scell Secondary cell
SGW Serving GateWay
SNR Signal to Noise Ratio
SSS Secondary Synchronization Signal
Tx Transmitter or transmission
UE User Equipment
UL UpLink
WLAN Wireless Local Area Network
With increasing numbers of smart phones and machines (such as sensors) connected to wireless networks, the amount of wireless data might increase 100 fold in the next five years. Already, smart phones are facing a lack of capacity in some networks. All methods to help with this lack of capacity are being examined.
One approach is to use unlicensed frequencies (e.g., ISM bands) for LTE operation, when available, in order to get more capacity for LTE. Using unlicensed bands for LTE presents a lot of challenges. This is due to the fact that LTE has been fundamentally designed for licensed bands with careful consideration of resource allocations, synchronization, scheduling, and interference management (to name a few aspects). By moving to the unlicensed band, many of those designed features cannot be easily retained. On the other hand, LTE accessing unlicensed bands has to coexist with many incumbent devices like BLUETOOTH (an open wireless technology standard for exchanging data over short distances) and WiFi (a technology that allows an electronic device to exchange data wirelessly over a computer network). Therefore, a careful consideration for sharing the spectrum from unlicensed bands is needed.